Hydrosilylation of vinyl-terminated polypropylene (PP) has proven to be a suitable method to prepare end-functional polymers. These techniques can be used for the compatibilization of inorganic fillers or polymer blends. In WO 97/47665, assigned to University of Waterloo and the disclosure of which is incorporated herein by reference, it has been shown that the hydrosilylation of the polymer can be performed in the melt phase, that is during processing, when a platinum catalyst is activated by a peroxide. WO 97/47665 specifically describes the preparation of linear structures, i.e. the preparation of polypropylene-polydimethylsiloxane (PDMS) block copolymers. This result was achieved (WO 97/47665) by reaction of a vinyl-terminated PP with a mixture of a hydride-terminated polydimethyl-siloxane/Pt/t-butylhydro-peroxide solution in a batch mixer or single-screw extruder at processing temperatures of about 170° to about 220° C. Thus, melt phase hydrosilylation makes it possible to produce PP-PDMS block copolymers. This product is of considerable interest since it is known that polydimethylsiloxanes have a low glass transition temperature and a high gas permeability. By in-situ synthesis of block copolymers, reactive blending of both polymers becomes possible and thus interesting blend properties can be achieved.
However, to prepare the vinyl-termination on the chain-end necessary for the preparation of the block copolymers, the polypropylene was degraded by peroxides prior to the hydrosilylation reaction. The degradation has led to a decrease in the molar mass as well as in the polydispersity. These effects reduced the mechanical properties of the material, such as the elongation at break and the tensile impact strength. Hence, the application of the products produced according to the procedures of WO 97/47665, was restricted.